Process for making 2,2-bis aryl trihaloethanes



number of current maganme articlas To date quantities of a halosulfonicacid instead. the production of DDT has depended upon the ,Q F? ourinvention part be employment of large Volumes of 93% H2504 in OOVl-OuS,and W111 in pait appear heiemafter. order to effect the condensationbetween anhy- For a more complet? lmdersfiandmg of the drous chloral(ccncnoa and chlorbenzene We and scope of ms invemlon reference may(CeHsCl). The chemical literature contains sevhad h followmg detalleddescnptmn y refere to condensations of this type thereof, wherein anumber of presently preferred wherein some and, compound is condensedwith methods of practiclng the invention are fully dean aldehyde to form1,1 diarylethanes. For exscribed. ample, Baeyer (Ber. 7, 1198 (1873))succeeded Numerous expellments have 1601 t0 he Conin condensingacetaldehyde (CHBCHO) with bencl i n th t th rol p y by 2 4 in he D zeneto form 1,1 diphenylethane, using, however, synthesis is one of speci icCatalysis rather th 606 grams of concentrated H2804 for every 0.06 oneof simple dehydration. The mechanism for mol of paraldehyde((CHaCI-IOM). This type the action of H2804 appears to be as follows: ofcondensation conducted in the presence of a 30 large excess ofconcentrated H2504 is still be- (1) ing conducted today, specifically inthe synthesis CCIBOH GPO-H 02011 of DDT. OH

2 U canon-osmon O01 CCl -CHOOI nlso,

tn (5H OOl -OH 01+ E 804 0013-4311 01+ H2O Ida -SO2OH 4 U CGl -THC C1+C1cot-onOcm-mso,

Th object of this invention, generally stated, Reaction 3, above, fortwo reasons, is believed is the provision of an improved method of con-7 to be responsible for the necessity of using large densing an alkylcompound with an aryl com- 59 quantities of concentrated H2804. First, ahuge pound by the employment of a halosulfonic acid. excess ofconcentrated HzSO-a nullifies the dilu- More specifically, an importantobject of the tion efiect of the acid by the water formed and inventionis the provision of a new and imsecond, the reversibility of equation 3is miniproved method of condensing an aliphatic alco- H mized by theremoval of H20 through a large hol or alcoholate with an aromatichydrocarbon excess of concentrated H2804. through the aid of ahalosulfonic acid. Another These difficulties have been overcome by theimportant object of the invention is the provision use of a halosulfonicacid (for example, chlorof an improved method of carrying outcondensasulfonic acid or fluosulfonic acid, both being tion typereactions between aryl compounds and commercially available products) ascondensing i atented May 22, i 1 UNITED STATES PATET ()FFICE PROCESS FORMAKING 2,2-BIS ARYL TRIHALOETHANES Walter H. C. litueggeberg and WillardE. Catlin, United States Army, and Walter I A. Cook, Akron, Ohio,assignors to the United States of America as represented by theSecretary of War No Drawing. Application March 2'7, 1945, Serial N0.535,200

14 Claims. (01. 260-649) Ihe invention described herein may be manu-Still another important object of our invention factured and used by orfor the Government for is the provision of a new and improved method or"governmental purposes without the payment to producing DDT involving theuse of a halosulus of any royalty thereon. ionic acid to bring about thecondensation b This invention relates, generally, to condensa- 5 tweenchlorbenzene and chloral, chloral hydrate, tion type reactions whereinalkyl aryls are proor chloral alcoholate. This method of making duced bythe aid of halosulf-onic acids. The in- DDT is considerably moreefficient and cheaper vention relates, particularly, to new and 1111-than present methods of making this compound. proved methods ofproducing the pesticide popu- The superiority of this new method is, ina large lariy known as DDT, the chemical name of which 10 measure, dueto thejeasibility of using chloral is -bis (p-chloroph nyl hydrate orchloral alcoholate in place of anhy- P has been found} t0 be an9140531191113 drous chloral, and to the elimination of the use tlcldeand has been Wldely used by mlhtary of the large volume of concentratedsulfuric acid forcesuin QL F and in tropics' Its heretofore required,and the utilization of small peacetime possibilities have been discussedin a 15 aldehydes by the aid of a halosulfonic acid. agent for chloralhydrate and chlorbenzene to form DDT. An added advantage in the use of ahalosulfonic acid is the fact that chloral hydrate (CCla-Cl-HOI-Dz, acommercial product) may be used as reagent in place of chloral, which isless stable and less satisfactorily stored and shipped than is thehydrate or alcoholate and which would have to be prepared separatelyfrom chloral hydrate by the required quantity of concentrated H2SO4 inexcess of that required for the H2804 in the DDT condensation, describedabove;

The action of a halosulfonic acid is described in the following set ofequations, wherein X designates a halogen:

Since recrystallization from ethanol results in the loss ofapproximately 35% of the product, to the mother liquor, the crude DDTmay instead be further purified by washing with a 1% aqueous solution ofa wetting agent (such as Aerosol OT or Tergitol 4 to 7).

cola-Z3001 XSOaH CClr-iHOCI HX SOQOH 82.7 parts by weight of chloralhydrate are placed in a suitable reaction vessel provided withthermometer, stirrer, dropping funnel, and gas outlet tube. From thedropping funnel, 58.3 parts by weight of commercial chlorsulfonic acidare added slowly, keeping the temperature between C. and 10 C. andavoiding a too violent evolution of HCl gas. After the addition ofchlorsulfonic acid is complete, the mixture is allowed to stir at10-'-20 C. until all of the chloral hydrate crystals have dissolved.112.6 parts by weightof chlorbenzene are added to the reaction vessel ata rate slow-enough so the reaction mixture remains at 20 C. Thisaddition requires about -10 minutes. An additional 58.3 parts by weightof chlorsulfonic acid are then added dropwise from the dropping funnelover a period of approximately 2 hours, at which time a heavyprecipitation of the DDT has become visible. Stirring is continued foran additional 3-5 hours. When the reaction is complete, 200 parts byweight of an ice-H2O mixture is added and the product filtered off on aBiichner funnel. Air is allowed to draw through the funnel for anadditional 12 hours. Yield, crude DDT=94.5 g. (53% of theory) M. P.95-98 C., 102-103 C., depending upon the extent of the water wash andtimeof drying. Upon recrystallization from ethanol, a product melting at107108 C. is obtained.

By steam distilling the oily layer of the filtrate, mentioned above, anadditional -15% of DDT may be recovered from the residue thus bringingthe total yield to 63-68 This method may also be carried out attemperatures less than or-greater'than the 10 -20 C. temperature rangeset forth in the presently preferred method. The process may also beconducted in the presence of inert solvents such as carbontetrachloride, chlorobenzene, etc. For example, temperatures varyingbetween --5 C. and 39 C. yielded the followin results:

Reaction Tempcra- Yleld, Solvent ture, C. fi g Per Cent 5 t0 0 5 38. 4010 2 40. 2 10 6 57. 5 20 6 69. 1 30 6 74. 0 -20 6 71. 3 0 7 51. 0 7 74.5 0 6 54. 5 1O 6 63. 5 G 76. 1

It is believed that this method may be conducted at any temperature from0 C. or lower and C. or higher, the higher temperature, however, beingdetrimental to the purity of the product.

The three following examples illustrate methods of making DDT similar tothe method of Example 1, but wherein the chlorsulfonic acid may bereplaced with fluosulfonic acid, and/or the chloral hydrate replacedwith chloral alcoholate (hemi-ethylacetal) or the crude product obtainedfrom the chlorinationof ethanol.

EXAMPLE 2 In a reaction vessel fitted with a stirrer, inlet tube,thermometer, and apparatus for absorption of the hydrogen fluorideby-product, was placed 83 parts by weight of chloral hydrate. Withstirring, 50 parts of fluosulfcnic acid was added slowly. Immediatelyfollowing this addition, 113 parts chlorbenzene was run in and welldispersed in the reaction mixture. The reaction vessel was cooledexternally, and the addition was made at such a rate that thetemperature was held below 30 C. This required about ten minutes. Thenan additional 60 parts of fluosulfonic acid (including a overall excess)was add-ed, and stirring was continued for six hours, while thetemperature was maintained at 30 C. Cooling was necessary during thefirst hour of this period. Considerable precipitation had occurred, andthis material was filtered ofi at the end of the reaction. After washingand drying the precipitate,.there was obtained 117.5 parts crude DDT, M..P. 93-103 C. The filtrate from the reaction mixture was poured intowater and the oil residue solidified upon coolin and had a M. P.

of 81-88 C. It was added to the first precipitate.

Total yield of crude DDT was 149 parts, or 84% of theoretical.Recrystallization of the product from ethyl alcohol gave pure DDT, M. P.107- 108 C., which gave no depression of M. P. upon admixture with asample of authentic material.

EXAMPLE 3 Use of chloral alcoholate in preparation of DDT Chlorobenzene(112.5 parts by weight) and 97 parts by weight of chloral alcoholateOCgH are placed in a suitable reaction vessel which is fitted with aneificient stirrer, a thermometer,

104 parts, or 59% of the theoretical, is obtained I of product meltingat 85-96 (3., and a chlorine content of 49.65% (theory for DDT 50.0%).

The acid filtrate is poured on crushed ice and the heavy oil whichseparates is steam distilled.

A total of about 2 parts of unreacted chlorobenzene is recovered. Thenonvolatile residue amounts to about 38 parts, giving a yield based ontotal crude product of 79.5%.

EXAMPLE 4 Use of fluosulfonic acid and chloral alcoholate in preparationof DDT A solution of 96 parts of chloral hemi-ethylacetal in 113 partsof chlorobenzene was poured into a suitable reaction vessel fitted witha mercury-seal stirrer, dropping funnel, thermometer, and apparatus forabsorption of hydrogen fluoride. From the dropping funnel, 110 parts offiuosulfonic acid was added slowly with stirring and external cooling tokeep the, reaction term perature below 30 0. Then stirring at 30 (3.:was continued for 6 hours. The precipitate was. filtered off, washed,and dried; melting point -99 C. The filtrate was poured into water andthe oily layer steam distilled to remove unreacted chlorobenzene. Theresidue (M. P. 81- 88 C.) was combined with the first precipitate.Crystallization of this crude DDT from ethyl alcohol gave a productmelting at 107-108 C. This gave no depression in M. P. when mixed withan authentic sample of pure DDT.

In the preparation of DDT by the above methods of Examples 3 and 4 animproved yield (based on the chloral alcoholate) may be obtained byusing a slight excess of chlorobenzene. The reaction rate may also beincreased by carrying out the process at a higher temperature; however,at. temperatures above about 65 C. appreciable amounts ofsulfur-containing by-products are formed. The reactions may also becarried out at temperatures lower those given in the examples.

The invention may be employed to produce analogs of DDT as illustratedby the following examples:

EXAMPLE 5 Use of chloral alcoholate in preparation of benzene analogof'DDT Chloral alcoholate (48 parts) was melted and diluted with 39parts of benzene. To the stirred mixture there was added 58 parts ofchlorosulfonic acid while the temperature of the mixture was held at15-25" C. After a reaction period of six hours the mixture was treatedwith 250 parts of ice water.

An oily product separated from which volatile impurities were removed bysteam distillation. After recrystallization from 95% ethanol a prodnotwas obtained which melted at Gil-63 C., and which showed no depressionof the melting point when mixed with an authentic sample of 1,1-diphenyl2,2,2-trichloroethane.

EXAMPLE 6 Use of chloral alcoholate in preparation of bromine analog ofDDT To a well-stirred mixture of 48 parts of chloral alcoholate and 79parts of bromobenzene, there was added slowly 58 parts of chlorosulfonicacid at a reaction temperature of 15-25 C. After a reaction period of 6hours the mixture was treated with ice water (250 parts) An insolubleoil separated which was steam distilled and 21 g. of unreactedbromobenzene recovered. There remained 68 parts of a solid, non-volatileresidue. A portion of this material was twice crystallized from ethylalcohol giving a product which melted sharply at -14? C. A mixed M. P.with an authentic sample of 2,2-bis(p-bromophenyl) 1,1,1-trich1oroethaneshowed no depression. A yield of 62% of theoretical was obtained.

EXAMPLE '7 Use of fluosulfom'c acid as catalyst in preparatz'on ofdiphenyltrzchlorethane from chloral hydrate The benzene analog of DDTwas prepared by substituting 78 grams of benzene for the chlorobenzeneas used in Example 2 above. After the reaction had been run for 4 hoursat 30 C., the mass had almost completely solidified. It was broken up inice water, washed thoroughly, filtered, and dried. The product (140grams) melted at 57-60 C. Recrystallization from ethyl the 7 alcoholraised the M. P. to (ii-62 C. Mixture with an authentic sample ofdiplienyltrichlorethane gave no depression in melting points.

EXALIPLE 8 Use of fluosulfom'c acid as catalyst in preparation of dip-brmphenyltrichlorethaine from chloral hydrate A bromine-containinganalog of DDT was-prepared by substituting 157 grams of brombenzene forthe chlorobenzene in the procedure substantially that described inExample 2. After the reaction was held at 30 for 6 hours the mixture wasfiltered, and the precipitate washed and dried. There was obtained 95parts of the crude product, M. P. 130-138 C. Recrystallization fromethyl alcohol raised the M. P. to 140- 141" C. Mixture with an authenticsample of di-p-bromphenyltrichlorethane gave no depression in themelting point.

The advantages of this invention are not confined to completelyeliminating the use of sulfuric acid, and it is possible through thisinven tion to efiect the condensation between chloralhydrate andchlorobenzene by employing a mixture of a halosulfonic acid and sulfuricacid or a halosulfonic and fuming sulfuric acid (oleum) as illustratedby the following example:

EXAMPLE 9 82.7 parts by weight of chloralhydrate is placed in a suitablereactor equipped with stirrer, thermometer, gas exit tube, and droppingfunnel. 58.3 parts by weight of chlorsulfonic acid is added withstirring at such a rate that the temperature of the reaction mixturedoes not exceed 10 C. When all the chloralhydrate crystals havedissolved and the evolution of H01 gas has virtually ceased, 112.5 partsby weight of chlorbenzene is added with stirring to the reaction mixtureat a rate such that the temperature does not exceed C. From the droppingfunnel, 143.0 parts by weight of 28% oleum (H2SO4.SO3) is added dropwisewith vigorous stirring over a period of 10-30 minutes. Stirring iscontinued from 2-6 hours at 20 C. after the addition of the oleum iscomplete. The product is Washed with Water, filtered, and dried. YieldDDT=-60% of theory.

Although from the cost standpoint, it is now preferred to usechloralhydrate instead of anhydrous chloral, through the use of ahalosulfonic acid, this invention also lendsitself to the condensationof anhydrou chloral (CC13GHO) With chlorbenzene. This reaction, alsorequires the metathetical quantity of the halosulfonic acid,- beinghowever, only one-half that required for an equivalent quantity ofchloral hydrate.

The following example illustrates the use of anyhdrous chloral:

EXAMPLE 10 73.7 parts by weight of anhydrous chloral is mixed with 112.5parts by weight of chlorbenzene at 10 C. in a suitable reaction vesselequipped with thermometer, stirrer, gas exit tube, and dropping funnel.From the dropping funnel 58.3 parts b Weight of chlorsulfonic acid isadded dropwise over a period of 30 minutes keeping the temperature atl020 C. After addition of the chlorsulfonic acid is complete, stirringis allowed to continue for an additional 5 /2 hours t 10-20 C. Theproduct is washed 3 times with water, filtered, dried, and weighed.Yield DDT=50-60% of theory.

The invention appears to have wide application in the condensation ofaromatic hydrocarbons with many aliphatic alcohols and many aldehydes.The condensation reactions may, in certain instances, be advantageouslycarried out in the presence of an inert solvent, such as carbontetrachloride. Experience has shown that secondary and tertiary alcoholsare, as a class, considerably more susceptible to our new type ofcondensation reaction employing a halosulfonic acid, than are theprimary alcohols. The following table outlines a number of condensationreactions in addition to the examples described in detail above.

TABLE Condensations by use of a halosulfonz'c acid Alcohol or AldehydeUsed Aryl Compound Used Analytical Data On Product Obtained ProductBenzene..

Toluene Brombrnzcne.

| Per cent 0 found, 59.0

Per cent 0 calc, 58.9 Per cent H found, 3.9 Per cent H calc., 4.0 Percent 01 found, 37.2 Per cent 01 cold, 37.3

Per cent found C, 61.2 Per cent 0 calm, 61.3 Per cent H found, 4.8 Percent H 02110., 4.8 Per cent Cl found, 34.8 Per cent O1 0210., 33.9

M. P., 138-139 C.

Per cent C found, 38.2 Per cent C calc., 37.9 Per cent H found, 2.2 Percent H calc.,'2.1 Per cent Cl found, 22.8 Per cent 01 calc., 24. 0 Percent Br found, 35.90 Per cent Br 01110., 36.0

TABLE-Continued Condensations by use of a halosulfonic acidContinuedExample Alcohol or Aldehyde Aryl Com ound Anal tical Data On No. UsedUsed Product Obtamed Product 1E1 Br 14 do BrC BrC OMIDO Heavy oil (notanalyzed).

Br Br Ell C1 1s --d0 01 0 013 3601 Do- 1?: o era-(761* M. P., 4o-42 c.

CHOH

CH OH Ohlorbenzene Benzene (a) Benzene Isomeric Mixture @CEO CH3 C 3Toluene (a) (IIHOCH Isomeric Mixture on, (b) CHQCH CHCH;

l CH

CH3 CH Per cent 0 found, 52.5 Per cent 0 calc., 52.3. Per cent H found,2.9 Per cent H calc., 2.8 Per cent Cl found, 32.9 Per cent Cl calm, 33.1Per cent F found, 11.7 Per cent F calc., 11.8

Cgrgversion of alcohol, B. PI, 2l42l6 o. 1so

mm. Per cent Cl found, 21.0

Per cent Cl calc., 21.0 N20 1. 509

((1) Conversion of alco- (b) Conversion of alcohol,

Conversion of alcohol,

18-20%. M. P. 25-26 C.

((1) Conversion of alcohol,

B. P, 169 C./760 mm. N709 1.492

Per cent H found, 10.9 Per cent H calc., 11.6

(a) Conversion of alcohol,

B. P., 175178 C./760

TABLEContinued Aryl Compound Example No. Used Alcohol or Aldehyde UsedProduct Obtained Analytical Data On Product 22 Toluene CBraCHO IsomericMixture (a) Conversion of alcohol,

Since certain further changes and modifications may be made in theforegoing processes and procedures, and different embodiments of theinvention will suggest themselves to those skilled in the art, it isintended that all matter described above will be taken as illustrativeand not in a limiting sense.

We claim:

1. The process for making 2,2-bis aryl 1,1,1,

trihaloethanes which comprises condensing at a temperature below' 50 C.2 moles of an aromatic compound selected from the group consisting ofbenzene, toluene, and h'alobenzenes containing at least one replaceablehydrogen atom, with one mole of an aldehyde compound of the groupconsisting of chloral, chloral hydrate, chloral alcoholate and bromal inthe presence of at least a methathetical amount of fluosulphonic acid.

2. The process of claim 1 wherein the aromatic compound is fluobenzene.

3. The process of claim 1 wherein the aromatic compound is bromobenzene.

4. The process of claim 1 wherein the aromatic compound is benzene.

5. The process of claim 1 wherein the aromatic compound ischlorobenzene.

6. The process of claim 1 wherein the aldehydic compound is chloralhydrate.

7. The process of claim 1 wherein the aldehydic compound is chloralalcoholate.

8. The process of claim 1 wherein the aldehydic compound is anhydrouschloral.

9. The process of claim 1 wherein the aldehydic compound is bromal.

10. The method of making 2,2-bis (p-chlorophenyl) 1,1,1-trichloroethane,which comprises reacting, at a temperature below C, one mol of chloralwith approximately two mols of chlorobenzene in the presence of at leastone mol of fiuosulphonic acid.

11. The method of making 2,2-bis. (p-chlorphenyl)1,1,1-trichloroetlrane, which comprises, adding about 1 part by weightof fiuosulfonic acid to about 1.66 parts b weight of chloral hydrate,adding about 2.26 parts by weight of chlorbenzene to'the mixture whilemaintaining the reaction temperature below about 30 C., and adding about1.2 parts by weight of fiuosulfonic acid to the reaction mass whilemaintaining the reaction temperature at about 30 C.

12. The method of making 2,2-diphenyl 1,1,1- trichloroethane, whichcomprises, adding about 1 part by Weight of fluosulfonic acid to about1.66 parts by weight of chloral hydrate, adding about 1.56 parts byweight of benzene to the mixture while maintaining the reactiontemperature below about 30 C., and adding about 1.2 parts by weight offluosulfonic acid to the reaction mass while maintaining the reactiontemperature at about 30 C.

13. The method of making 2,2-bis (p-bromophenyl) 1,1,l-trichloroethane,which comprises, adding about 1 part by weight of fluosulfonic acid toabout 1.66 parts by weight of chloral hydrate, adding about 3.14 parts bweight of bromobenzene to the mixture while maintaining the reactiontemperature below about 30 C., and adding about 1.2 parts by Weight Offluosulfonic acid to the reaction mass while maintaining the reactiontemperature at about 30 C.

14. The method of making 2,2-bis (p-chlorphenyl) 1,1,1-trichloroethane,which comprises, forming a mixture of about 1 part by weight of chloralalcoholate and about 1.18 parts by Weight of chlorbenzene, adding about1.17 parts by weight of fluosulfonic acid to the mixture 'while keepingthe reaction temperature not in excess of 30 C.

WALTER H. C. RUEGGEBERG. WILLARD E. CATLIN. WALTER A. COOK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,259,723 Ballard et a1 Oct. 21,1941 2,349,211 Tulleners May 16, 1944 2,500,961 Rueggeberg etal. Mar.21, 1950

1. THE PROCESS FOR MAKING 2,2-BIS ARYL 1,1,1, TRIHALOETHANES WHICHCOMPRISES CONDENSING AT A TEMPERATURE BELOW 50* C. 2 MOLES OF ANAROMATIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF BENZENE,TOLUENE, AND HALOBENZENES CONTAININ AT LEAST ONE REPLACEABLE HYDROGENATOM, WITH ONE MOLE OF AN ALDEHYDE COMPOUND OF THE GROUP CONSISTING OFCHLORAL, CHLORAL HYDRATE, CHLORAL ALCOHOLATE AND BROMAL IN THE PRESENCEOF AT LEAST A METHATHETICAL AMOUNT OF FLUOSULPHONIC ACID.